Such swivelable connector brackets are used, for example, in connection with automatically working plug-in coupling systems of supply lines, such as are also disclosed in DE 101 55 056. In the known system, a connector bracket can swivel about the king pin, and this is introduced into the insertion opening of the fifth wheel when hooking up the semitrailer. In this end position, a contacting between a socket on the tractor side and a connector arranged in the connector bracket then takes place. In one simple embodiment, the supply lines, such as current and/or compressed air lines, are led out to the rear from the connector bracket and fastened on the semitrailer with enough slack that the semitrailer is able to swivel out when driving on a curve. But due to the slack in the lines, there have always been instances of damage or breaking of the lines.
To lessen the danger of line breakage, it is proposed in DE 10 2004 044 992 to make the supply lines taut and spring-loaded with a line accumulator which can be mounted on the underside of the semitrailer, making possible an unwinding of the line while driving along a curve. For this, the known line accumulator has a flat cable pulley as a winding drum, on which a segment of the supply line is wound up. The basic drawback of this device, however, is the low lifetime of the supply line, since the winding circumference of the supply line is relatively small and therefore the supply line is subject to a substantial bending stress, which often proceeds as far as incipient damage to the line material. A further aggravating factor is that the supply line is subject to an alternate bending while driving on a curve, so that irreversible damage can sometimes be caused to the material of the supply line. A further drawback of the known line accumulator is that, due to the exposed position beneath the semitrailer, the ISO specified semitrailer contour is not fulfilled.